Chapter 4: Biodiversity and Evolution

Chapter 4: Biodiversity and Evolution
Biodiversity & Evolution Evolution and Biodiversity; Chapter 4

4-1: What is biodiversity and why is it important?
Concept 4-1: The biodiversity found in genes, species, ecosystems, and ecosystem processes is vital to sustaining life on earth

Chapter Overview Questions
How do extinction of species and formation of new species affect biodiversity? What is the future of evolution, and what role should humans play in this future? How did we become such a powerful species in a short time?

Chapter Overview Questions
How do scientists account for the development of life on earth? What is biological evolution by natural selection, and how can it account for the current diversity of organisms on the earth? How can geologic processes, climate change and catastrophes affect biological evolution? What is an ecological niche, and how does it help a population adapt to changing the environmental conditions?

CASE STUDY: Conserving Shark Species
400 known species 6 Human deaths per year from shark attacks 79-97 million sharks killed every year Fins Organs, meat, hides Fear 32% shark species threatened with extinction Keystone species Rarely get cancer/infections

Endangered Scalloped Hammerhead Shark
Threatened Whale Shark- Harmless Species to Humans

4-1 What Is Biodiversity and Why Is It Important?
Concept 4-1 The biodiversity found in genes, species, ecosystems, and ecosystem processes is vital to sustaining life on earth.

Biodiversity Is a Crucial Part of the Earth’s Natural Capital (1)
Species: set of individuals who can mate and produce fertile offspring ESTIMATED: 8 million to 100 million species Best guess ~10-14 million 1.9 million identified Up to half of earth’s species are mostly in rain forests and oceans

Encyclopedia of Life Scientists are working on a website devoted to summarizing all the basic info on the world’s known and named species Continually updated as more species are discovered

Biodiversity Is a Crucial Part of the Earth’s Natural Capital (2)
4 Components of Biodiversity Species diversity The # and abundance of different species present in different communities Genetic diversity The Variety of Genetic Material Ecosystem diversity Biomes: terrestrial regions with distinct climates/species Different terrestrial and aquatic ecosystems on earh Functional diversity Different Biological and chemical processes on earth Ex. Energy flow, matter cycling Biodiversity is an important part of natural capital

Genetic Diversity The variety of genetic material within a
Functional Diversity The biological and chemical processes such as energy flow and matter recycling needed for the survival of species, communities, and ecosystems. Ecological Diversity The variety of terrestrial and aquatic ecosystems found in an area or on the earth. Solar energy Chemical nutrients (carbon dioxide, oxygen, nitrogen, minerals) Heat Heat Heat Decomposers (bacteria, fungi) Producers (plants) Consumers (plant eaters, meat eaters) Heat Heat Figure 4.2: Natural capital. This diagram illustrates the major components of the earth’s biodiversity—one of the earth’s most important renewable resources and a key component of the planet’s natural capital (see Figure 1-4, p. 9). See an animation based on this figure at CengageNOW. Question: What role do you play in such degradation? Genetic Diversity The variety of genetic material within a species or a population. Species Diversity The number and abundance of species present in different communities. Fig. 4-2, p. 82

Different variations of Caribbean snail
Different variations of Caribbean snail. Which component of biodiversity does this exemplify? Figure 4.4: Genetic diversity among individuals in a population of a species of Caribbean snail is reflected in the variations in shell color and banding patterns. Genetic diversity can also include other variations such as slight differences in chemical makeup, sensitivity to various chemicals, and behavior. Fig. 4-4, p. 83

Coastal mountain ranges Mississippi River Valley
Terrestrial Biomes Denver Baltimore San Francisco Las Vegas St. Louis Coastal mountain ranges Sierra Nevada Great American Desert Rocky Mountains Great Plains Mississippi River Valley Appalachian Mountains Figure 4.5: The major biomes found along the 39th parallel across the United States are shown in this diagram. The differences in tree and other plant species reflect changes in climate, mainly differences in average annual precipitation and temperature. Coastal chaparral and scrub Coniferous forest Desert Coniferous forest Prairie grassland Deciduous forest Fig. 4-5, p. 84

Classifying Homo Sapiens
Figure 2 This diagram illustrates the taxonomic classification of the latest human species, Homo sapiens sapiens. Supplement 5, Fig. 2, p. S19

Science Focus: Have you thanked insects today?
Very Important part of the earth’s natural capital Often classified as pests competition Spread human disease bite/sting Natural services of insects include Pollination Population control Loosen/renew soil Reproduce and develop new genetic traits rapidly Very resistant to extinction How is this good for us?

Science Focus: Insects
Ultimate lesson to be learned: Although insect may not need us [humans], we and most other land organisms need them

Individuals Matter: Edward O. Wilson: A Champion of Biodiversity
Loved bugs as a kid Specialized in ants Widened scope to earth’s biodiversity Theory of island biogeography First to use “biodiversity” in a scientific paper

Edward O. Wilson Figure 4.B: Edward O. Wilson. Fig. 4-B, p. 85

4-2 How Does Earth’s Life Change Over Time?
Concept 4-2A: The scientific theory of evolution explains how life on earth changes over time through changes in the genes of population Concept 4-2B: Populations evolve when genes mutate and give some individuals genetic traits that enhance their abilities to survive and to reproduce offspring with these traits (natural selection).

Biological Evolution by Natural Selection Explains How Life Changes over Time (1)
Fossils- mineralized/petrified replicas of bones, skeletons, teeth, shells, leaves, and seeds or impressions of such items Found in rocks, glacial ice, different layers of earth Physical evidence of ancient organisms Reveal what their external structures looked like Fossil record: entire body of fossil evidence Uneven and incomplete Only have fossils of 1% of all species that lived on earth Some species leave no fossil, or fossils decompose

Fossilized Skeleton of an Herbivore that Lived during the Cenozoic Era
Figure 4.6: This fossilized skeleton is the mineralized remains of an herbivore that lived during the Cenozoic era from 26 to 66 million years ago. Fig. 4-6, p. 86

Biological Evolution by Natural Selection Explains How Life Changes over Time (2)
Biological evolution: how earth’s life changes over time through changes in the genetic characteristics of populations Darwin: Origin of Species Natural selection: individuals with certain traits are more likely to survive and reproduce under a certain set of environmental conditions Theory of Evolution: All Species descended from earlier ancestral species (aka- life came from life) Huge body of evidence

Evolution by Natural Selection Works through Mutations and Adaptations (1)
Populations evolve by becoming genetically different Genetic variations First step in biological evolution Occurs through mutations in reproductive cells Mutations: random changes in DNA molecules From hiccups in DNA transcription From x-rays, radioactivity, natural & human-made chemicals

Evolution by Natural Selection Works through Mutations and Adaptations (2)
Natural selection: acts on individuals Second step in biological evolution after mutation Adaptation to environment may lead to differential reproduction Some species with the beneficial trait survive and produce more offspring than other members with out the trait Eventually those with out the trait diminish Those with the trait increase in abundance Genetic resistance: ability of one or more members of a population to resist a chemical designed to kill it Example: Antibiotic resistant bacteria

including genetically resistant ones,
A group of bacteria, including genetically resistant ones, are exposed to an antibiotic (d) Eventually the resistant strain replaces all or most of the strain affected by the antibiotic (c) The genetically resistant bacteria start multiplying (b) Most of the normal bacteria die Figure 4.7: Evolution by natural selection. (a) A population of bacteria is exposed to an antibiotic, which (b) kills all individuals except those possessing a trait that makes them resistant to the drug. (c) The resistant bacteria multiply and eventually (d) replace all or most of the nonresistant bacteria. Normal bacterium Resistant bacterium Fig. 4-7, p. 87

Summary of Biological Evolution
Evolution by natural selection in a nutshell: Genes mutate Individuals are selected based on possession of successful traits Populations evolve such that they are better adapted to survive AND reproduce under existing environmental conditions It is important to understand evolution occurs over generations- NOT within individuals Individuals are naturally selected Populations evolve over time (change over time)

Case Study: How Did Humans Become Such a Powerful Species?
Success attributed to 3 adaptations Strong opposable thumbs Walk upright Complex brain Adaptations that make a species successful now do not ensure survival when environment changes Our own environment is rapidly changing Will we be able to adapt to these changes?

Adaptation through Natural Selection Has Limits
Adaptive genetic traits must precede change in the environmental conditions Adaption can only occur when that trait is already present in the population Reproductive capacity Species that reproduce rapidly and in large numbers are better able to adapt Unlike weeds, cockroaches, rats, etc., some species cannot reproduce in large numbers or rapidly

Three Common Myths about Evolution through Natural Selection
“Survival of the fittest” is not “survival of the strongest” Fitness= reproductive success (NOT strength) Organisms do not develop traits out of need or want Giraffe’s necks No grand plan of nature for perfect adaptation No evidence that evolution steers toward making a super-species

Natural Selection of the Kernel Hunters
There are 3 types of kernel hunters hunters on Utensiles Island Forkus Utensilus Knifus Utensilus Spoonus Utensilus Each hunter competes with the other for the same resource to survive (corn kernels)

Island Background Info
There are currently 3 individuals who make up the Utensiles community on the island- one of each species Depending on how many kernels each species gets, the hunter will spontaneously reproduce a certain number of additional members of its own species Each species may only gather kernels with their heritable beak faeture Each hunter can only hunt for a maximum of 12 seconds per generation

Resource Benefits If a hunter gathers:
>30 kernels: survives and reproduces 2 20-29 kernels: survives and reproduces 1 10-19 kernels: survives but does not reproduce <10 kernels: hunter dies

Help Keep track of the island population and diversity
Groups of 4 3 hunters (one of each species) 1 timer All group members record data for 4 generations Copy down data Tables on your own piece of paper

Generation 1- starts with population of 3 (1,1, and 1)
SPOON Knife Fork Initial population size 1 # of beans collected New Population size

Generation 2 starts with ending population from previous generation
SPOON Knife Fork Initial population size # of beans collected New Population size

Continue for 3 more generations
If you don’t collect enough beans, your hunter dies. If the dead hunter reproduced, the population is now minus 1 If population = 0- species is EXTINCT (i.e- no longer part of community competition)

Complete your Island Report
Formal report should include: Title Explanation of the island mechanics (brief- no more than 1 paragraph) Data Tables 1-Graph Analysis (see questions on next slide)

Complete Data and Analyses
Construct a graph of the data for the population changes of each species over the generations Answer the Analysis Questions in paragraph format Did one species’ population size increase more than others? Which one, and why? Did any species go extinct? Why What was the independent and dependent variable of this simulation? If the simulation were to continue, what would you expect to happen to the species diversity? Connect the findings of this simulation the the process of evolution. Explain how natural selection acts on the individual and evolution occurs over populations.

4-3 How Do Geological Processes and Climate Change Affect Evolution?
Concept 4-3 Tectonic plate movements, volcanic eruptions, earthquakes, and climate change have shifted wildlife habitats, wiped out large numbers of species, and created opportunities for the evolution of new species.

Geologic Processes Affect Natural Selection
Tectonic plates (giant solid plates breaking earth’s surface) affect evolution and the location of life on earth (2) ways: Shifted latitudes of continents/oceans, influencing climates Species physically move, or adapt, or form new species through natural selection (via movement of continents) Earthquakes Sudden movement of tectonic plates Cause fissures in earth’s crust- separates populations  speciation may occur Volcanic eruptions Occur along boundaries of tectonic plates Affect biological evolution by destroying habitats, reducing populations

225 million years ago 135 million years ago 65 million years ago
Present Stepped Art Fig. 4-8, p. 89

Climate Change and Catastrophes Affect Natural Selection
Ice ages followed by warming temperatures Retreating ice sheets = raised seal level, reduced land area Collisions between the earth and large asteroids New species Extinctions Cause shifts in ecosystem locations and create opportunities for evolution of new species

Northern Hemisphere Ice coverage
18,000 years before present Northern Hemisphere Ice coverage Modern day (August) Legend Figure 4.9: These maps of the northern hemisphere show the large-scale changes in glacial ice coverage during the past 18,000 years. Other smaller changes in glacial ice on mountain ranges such as the European Alps are not shown. Question: What are two characteristics of an animal and two characteristics of a plant that natural selection would have favored as these ice sheets (left) advanced? (Data from the National Oceanic and Atmospheric Administration) Continental ice Sea ice Land above sea level Fig. 4-9, p. 89

Science Focus: Earth Is Just Right for Life to Thrive
Temperature range: supports life Orbit size: moderate temperatures Liquid water: necessary for life Rotation speed: sun doesn’t overheat surface Size: gravity keeps atmosphere

4-4 How Do Speciation, Extinction, and Human Activities Affect Biodiversity?
Concept 4-4A As environmental conditions change, the balance between formation of new species and extinction of existing species determines the earth’s biodiversity. Concept 4-4B Human activities can decrease biodiversity by causing the extinction of many species and by destroying or degrading habitats needed for the development of new species.

How Do New Species Evolve?
Speciation: one species splits into two or more species For sexually reproducing species, new species forms when: One population of species evolved to a point where it no longer can breed and produce fertile offspring with members of another population who did not evolve Speciation happens in (2) ways: Geographic isolation: happens first; physical isolation of populations for a long period Reproductive isolation: mutations and natural selection in geographically isolated populations lead to inability to produce viable offspring when members of two different populations mate

Geographic Isolation Different groups of same population become separated (physically) Migration Physical barriers (mountain range, stream, road) Volcanic eruption Tectonic plate movement Wind, flowing water First step in speciation

Reproductive Isolation
After separated for long period of time Separated species adapt to new environment under natural selection Occurs at the genetic level due to mutation If rejoined with separated population long enough, cannot produce live, fertile offspring any longer

Spreads northward and southward and separates Early fox population
Adapted to cold through heavier fur, short ears, short legs, and short nose. White fur matches snow for camouflage. Arctic Fox Northern population Different environmental conditions lead to different selective pressures and evolution into two different species. Spreads northward and southward and separates Early fox population Gray Fox Figure 4.10: Geographic isolation can lead to reproductive isolation, divergence of gene pools, and speciation. Southern population Adapted to heat through lightweight fur and long ears, legs, and nose, which give off more heat. Fig. 4-10, p. 91

Extinction is Forever 3 possible futures for species when environmental conditions change: Adapt Move (if possible) Extinction Biological extinction Local extinction- over large region, not globally

Background extinction: typical low rate of extinction
Endemic species Found only in one area Particularly vulnerable to extinction Found on islands and unique areas i.e- tropical rainforests, have specialized roles Unlikely to migrate or adapt to new environment Background extinction: typical low rate of extinction All species go extinct eventually, however at a low rate Average annual background extinction: 1-5 species for ever million species Drastic environmental conditions shorten this rate

Golden Toad of Costa Rica, Extinct
Lived in a protected region, yet still went extinct in 1989 Figure 4.11: This male golden toad lived in Costa Rica’s high-altitude Monteverde Cloud Forest Reserve. The species became extinct in 1989 apparently because its habitat dried up. Fig. 4-11, p. 92

Mass Extinction Mass extinction: significant rise in extinction rates above background extinction rate Often a global event Fossil record suggests 3-5 mass extinctions over past 500 million years Provides opportunity for evolution of new species Fill unoccupied ecological roles or newly created ones Occurrences of mass extinctions usually followed by increase in species diversity via speciation ***Concept 4-4A-balance of speciation and extinction determines biodiversity

Extinction rates, before and now
Before: speciation kept ahead of extinction Species diversity increased over time Now: evidence suggests extinction rate now higher than any other time in past 65 million years Much of loss of biodiversity due to human (anthropogenic) activities

Science Focus: Changing the Genetic Traits of Populations
Artificial selection Use selective breeding/crossbreeding Genetic engineering (GMO), gene splicing Alter organisms DNA Transfer genes from 2 different species (fish and tomato) Create new drugs, pest-resistant plants, rapid growing animals Consider Ethics Morals Privacy issues Harmful effects Decreased nutrition, new allergens, increased toxicity, antibiotic resistance

Genetically Engineered Mice
6-mo old Genetically modified mouse Normal 6-mo old mouse Figure 4.D: These mice are an example of genetic engineering. The 6-month-old mouse on the left is normal; the same-age mouse on the right had a human growth hormone gene inserted into its cells. Mice with this gene grow two to three times faster than, and twice as large as, mice without it. Question: How do you think the creation of such species might change the process of evolution by natural selection? Fig. 4-D, p. 92

4-5 What Is Species Diversity and Why Is It Important?
Concept 4-5 Species diversity is a major component of biodiversity and tends to increase the sustainability of ecosystems.

Species Diversity: Variety, Abundance of Species in a Particular Place (1)
Species diversity- number and variety of species an ecosystem community contains Species richness (R): The number of different species in a given area Does not reflect dominance R= s Species evenness (E): Comparative number of individuals Measure how similar the abundances of different species are Equal/similar proportions: E=1 Unequal/dissimilar proportions: E decreases E= H/[ln(R)]

Shannon-Weiner Index Accounts for species evenness and richness together Determined by # of species and even distribution of individuals among those species Accounts for relative dominance Ranges from 0 (community with 1-species) to over 7 (very diverse community) H= -Σ(Pi*ln[Pi]) Pi= relative abundance= ni/N ni= # of individuals in species-i N= total number of individuals in all species

Species Diversity cont’d
Most tropical forests have high species evenness Also coral reefs, tropical lakes, ocean bottom zone Species diversity varies with geographical location Islands are good areas of study for species richness

Variations in Species Richness and Species Evenness
Figure 4.12: These two types of ecosystems vary greatly in species richness. An example of high species richness is a coral reef (left), with a large number of different species. On the other hand, this grove of aspen trees in Alberta, Canada (right) has a small number of different species, or low species richness. Fig. 4-12, p. 93

Science Focus: Species Richness on Islands
Species equilibrium model, theory of island biogeography Rate of new species immigrating should balance with the rate of species extinction Island size and distance from the mainland need to be considered The smaller the island is, and further from the mainland, more likely less species Edward O. Wilson

Species-Rich Ecosystems Tend to Be Productive and Sustainable
Species richness seems to increase productivity and stability or sustainability, and provide insurance against catastrophe How much species richness is needed is debatable Ed. Wilson- “The more species you have in a food web, the more likely you will have an insurance policy for the whole ecosystem.”

4-6 What Roles Do Species Play in an Ecosystem?
Concept 4-6A Each species plays a specific ecological role called its niche. Concept 4-6B Any given species may play one or more of five important roles—native, nonnative, indicator, keystone, or foundation—in a particular ecosystem.

Each Species Plays a Unique Role in Its Ecosystem
Ecological niche, niche Pattern of living: everything that affects survival and reproduction A Species’ “Role” in life Water, space, sunlight, food, temperatures Not to be confused with “habitat” Generalist species Broad niche: wide range of tolerance Eat variety of food, live in different places, etc Examples: mice, white-tailed deer, roaches Specialist species Narrow niche: narrow range of tolerance Opposite of generalist Example: shorebirds

Specialist Species and Generalist Species Niches
Figure 4.13: Specialist species such as the giant panda have a narrow niche (left) and generalist species such as the raccoon have a broad niche (right). Fig. 4-13, p. 95

Specialized Feeding Niches of Various Bird Species in a Coastal Wetland
Figure 4.14: This diagram illustrates the specialized feeding niches of various bird species in a coastal wetland. This specialization reduces competition and allows sharing of limited resources. Fig. 4-14, p. 96

Specialists vs Generalists
Which is better? Depends Specialists usually have fewer competitors when environmental conditions are constant Generalists have the option of tolerance or change What do you think most shark species are??

Case Study: Cockroaches: Nature’s Ultimate Survivors
3500 species Outlived dinosaurs Generalists Eat almost anything Live in almost any climate Some survived being frozen for 48 hours High reproductive rates What’s their purpose Serve as food for birds/lizards

Species Can Play Five Major Roles within Ecosystems
Native species- Normally live and thrive in a particular area Nonnative species Invasive, alien, exotic; Introduced into an area not normally found Indicator species Provide early warning signs of ecosystem damage Many bird species, butterflies Keystone species Roles have large effect on the types and abundance of other species Foundation species Play major role in shaping their communities

Indicator Species Serve as Biological Smoke Alarms
Provide early warning of damage to a community Usually vulnerable to Enviro. Change Can monitor environmental quality Trout Birds- found everywhere, affected quickly by environmental change Butterflies-association with various plants Frogs

Case Study: Why Are Amphibians Vanishing? (1)
Habitat loss and fragmentation Prolonged drought Pollution Increase in UV radiation Parasites Viral and fungal diseases Climate change Overhunting Nonnative predators and competitors

Case Study: Why Are Amphibians Vanishing? (2)
Importance of amphibians Sensitive biological indicators of environmental changes Adult amphibians Important ecological roles in biological communities Important food web interactions Genetic storehouse of pharmaceutical products waiting to be discovered Compounds in skin secretions useful as painkillers antibiotics, burn and heart disease treatment

Keystone Species Play Critical Roles in Their Ecosystems
Keystone species: roles have a large effect on the types and abundances of other species Exist in limited or small numbers Vulnerable to extinction Pollinators Top predators Regulate populations

Case Study: Why Should We Care about the American Alligator?
Largest reptile in North America 1930s: Hunters and poachers By 1960’s : 90% wiped out a keystone species Gator holes Nesting mounds Keep shore/open water free of invading vegetation 1967: endangered species 1977: comeback, threatened species

Foundation Species Help to Form the Bases of Ecosystems
Create or enhance their habitats, which benefit others Elephants Beavers Similar role of keystone species Major difference: keystone species usually do the job of foundation species and much more additionally

Three Big Ideas Populations evolve when genes mutate and give some individuals genetic traits that enhance their abilities to survive and to produce offspring with these traits (natural selection). Human activities are decreasing the earth’s vital biodiversity by causing the extinction of species and by disrupting habitats needed for the development of new species. Each species plays a specific ecological role (ecological niche) in the ecosystem where it is found.

FRQ Practice Read the following statement and answer the questions in essay style-response. Be sure to read the question completely and understand exactly what it is asking Never let your answer deviate from the prompt’s purpose!

FRQ Practice Complete in your notebook Write questions and answer
Answers should be complete essay style

Chapter 4: Biodiversity and Evolution

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